We judge another person’s knowledge of things we don’t understand by what they say or write about things we do understand. I learned that the hard way in one of my very first books.
The book was about management by exception, which was management fad of the day. In the book I described a procedure that a trucking company might use. I got it wrong. I relied on a single written source and didn’t check the facts.
We sent the manuscript out to some readers. Usually it took a month to get the reactions back, but this time one came back in a few days. The reader had circled the procedure I just mentioned. Then he wrote “This is wrong! You don’t know what you’re talking about!” in giant letters. There was other language that’s not fit for a work-safe blog.
My editor, Jon, pointed out that the reason the manuscript came back so fast was that the reader stopped reading where he made his comment. He knew the procedure I described and he knew I got it wrong. As far as he was concerned, the rest of the book probably wasn’t worth reading.
That’s how readers will treat your book. If you’re accurate about the things they know, they’ll trust you on the things they don’t know. But if you get something wrong and they catch you, that’s it. They stop reading. If they’re deciding whether to buy your book, they make a no-buy decision.
Always assume there’s an expert reader out there on everything you write, because there is